WO 97/23466 discloses compounds described as having an analgesic effect, having a general and a typical preferred formula:

WO 98/28275 further discloses compounds described as having an analgesic effect, having a general and a typical preferred formula:

WO 93/15062 discloses compounds which have been described as delta-opioid and mu-opioid receptor agonists, having (approximately) the formula:

Astra Aktiebolag, World Patent 98/28270 discloses compounds with analgesic activity mediated through the delta opiate receptor having the general formula:

The synthesis and binding affinities for 4-diarylaminotropane compounds of the general formula:
wherein R is hydrogen, methyl, propyl, hexyl, 2-ethylbutyl, allyl, 3,3-dimethallyl, cyclohexylmethyl, phenethyl, phenylpropyl, 2,2-diphenylethyl, 3,4-dimethoxyphenethyl, 4-fluorophenethyl, 2-furylmethyl; 3,4-methylenedioxybenzyl, cyano and X is N,N-dimethylamino, N,N-diethylamino, N,N-dipropylamino, N-methyl, N-ethylamino, N-methyl, N-propylamino, N-methyl, N-phenylamino, N-ethyl, N-(4-methyl)benzylamino, N-butyl, N-ethylamino, N-butyl, N-propylamino, [N-ethyl, N-(2-methyl)allyl]amino, hydroxy, O-t-butyl and 1-pyrrolidinyl; and, Y is hydrogen, methoxy and methylthio as δ-opioid agonists have been described (Boyd, R. E., Carson, J. R., Codd, E. E., Gauthier, A. D., Neilson, L. A and Zhang, S-P., Biorg. Med. Chem. Lett., 2000, 10: 1109-1111).
The 4-[aryl(8-azabicyclo[3.2.1]octan-3-yl)]aminobenzoic acid derivatives disclosed in the above reference are claimed as δ-opioid receptor modulators in World Patent 01/46191.
4-[(8-Alkyl-8-azabicyclo[3.2.1]octyl-3-yl)-3-arylanilino]-N,N-diethylbenzamides have also been described as selective δ-opioid ligands (Thomas, J. B., Atkinson, R. N., Rothman, R. B., Burgess, J. P., Mascarella, S. W., Dersch, C. M., Xu, H. and Carroll, F. I., Biorg. Med. Chem. Lett., 2000, 10: 1281-1284).
In addition, 3-(diarylmethylene)-8-azabicyclo[3.2.1]octanes are described as δ- and μ-receptor modulators in World Patent 01/66543.

N,N-Diaryl piperazinebenzamides have also been reported to be selective δ-opioid ligands (Nortey, S. O.; Baxter, E. W.; Codd, E. E.; Zhang, S.-P.; Reitz, A. B. Biorg. Med. Chem. Lett., 2001, 11: 1741-1743). A representative structure is illustrated below:

The foregoing reference compounds have been described as either delta- or mu-opioid receptor agonists or antagonists.
It is an object of the present invention to provide substituted (piperidin-4-yl)aminobenzamido compounds which are delta-opioid receptor modulators. It is also an object of the present invention to provide substituted (piperidin-4-yl)aminobenzamido compounds which are δ-opioid receptor agonists useful as analgesics. It is another object of the present invention to provide δ-opioid receptor antagonists useful for treating immune disorders, inflammation, neurological conditions, psychiatric conditions, drug abuse, alcohol abuse, gastritis, diarrhea, cardiovascular disorders or respiratory disorders. It is a further object of the present invention to provide a method for treating a disorder modulated by the δ-opioid receptor.